Question

numa PG A1 = 4 a 9 = 1024 calcule A12​

Answer 1

Explicação passo-a-passo:

a9=a1.(q)^8

4.(q)^8=1024

(q)^8=1024/4

(q)^8=256

(q)^8=(2)^8

q=2 (valor da razão dessa PG )

a12=a9.(q)^3

a12=1024.(2)^3

a12=1024.(8)

a12=8192

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Resposta :

8192

Answer 2

$a_{9}=a_{1}. {q} ^{8}$

$1024=4.{q}^{8}$

${q}^{8}=\frac{1024}{4}$

${q}^{8}=256$

$q=\sqrt[8]{256}$

$q=\sqrt[\cancel{8}]{{2}^{\cancel{8}}}$

$q=2$

$a_{12}=a_{9}.{q}^{3}$

$a_{12}=1024.{2}^{3}$

$a_{12}=1024.8$

$\boxed{\boxed{ a_{12}= 8192}}$